REPORT 


ENGINEERS  OF  THE  U.  S.  N£VY 

♦ 

UPON 


MASSACHUSETTS  INSTITUTE  OF  TECHNOLOGY, 

MARCH,  1877. 


BOSTON: 

FRANKLIN  PRESS:  RAND,  AVERY,  & COMPANY. 
1877. 


Digitized  by  the  Internet  Archive 
in  2017  with  funding  from 

University  of  Illinois  Urbana-Champaign  Alternates 


https://archive.org/details/reportofengineerOOunit 


POUNDS  OF  COAL  CONSUMED 

PER  NET  HORSE-POWER,  PER  HOUR, 

AS  SHOWN  BY  EXPERIMENTS  UPON  THE  UNDERMENTIONED 
STEAMERS. 


Boiler 

Pounds 

NAME 

KIND 

Kind 

Pressure 

above 

Actual 

of  Coal 
Consumed 

OF 

STEAMER 

OF 

ENGINE 

OF 

Steam  Used 

Atmos- 

phere. 

Cut-off 

per 

Net  Horse 
Power 

I1)S.  pr.  sq.  in. 

per  hour 

Michigan 

( Non-Com- 
( pound 

Saturated 

2 I 

•29 

4-5  i 

Mackinaw 

(( 

a 

35 

•43 

! 3-49 

1 

Eutaw 

(( 

a 

27 

•54 

3-84 

Dexter 

u 

(( 

67 

.29 

: 3*4  i 

Dallas 

u 

a 

32 

•31 

1 3.8  I 

! 

Bache 

1 

j Compound 
( Jacketed 

a 

80 

.20 

i 

2.66 

Pvush 

u 

a 

69 

.16 

2.7 1 

Georgeanna 

t Non-Com- 
1 pound 

Superheated 

33 

•31 

1 

2.58 

Adelaide 

U 

a 

34 

•39  1 

245 

Mackinaw 

u 

u 

39 

.29  : 

2.48 

1 

Eutaw 

u 

28 

•54  i 

2.99 

! 

Dear  Sir  : 


In  handing  you  a copy  of  the  report  of  Naval  Engineers,  upon 
experiments  at  the  Massachusetts  Institute  of  Technology,  I would 
draw  your  attention  to  what  had  already  been  proved  by  previous 
experiments. 

This  will  be  shown  by  the  accompanying  table,  from  which  it 
appears  that  the  Georgeanna,  Adelaide,  Mackinaw  and  Eutaw, 
working  with  superheated  steam  at  moderate  pressures  and  without 
jackets,  surpassed  the  performances  of  jacketed  Compound  Engines 
working  with  much  higher  pressures  and  much  greater  expansion. 

Had  the  pressures  in  the  first-named  steamers  been  8o  or  90 
lbs.,  the  power  would  have  cost  less  by  about  20  %,  even  without 
shortening  the  cut-off. 

This  shows  that  a very  satisfactory  result  may  be  reached  in 
single  engines,  although  by  compounding  and  superheating  for  both 
cylinders  a still  better  effect  may  be  produced 

The  experiments  at  the  Institute,  owing  to  leakage  and  the 
greater  radiation  from  a small  engine,  do  not  bring  out  so  fully  the 
advantages  of  superheated  over  saturated  steam,  but  they  demon- 
strate all  those  peculiarities  in  the  action  of  superheated  steam 
which  they  were  designed  to  show,  and  the  necessity  for  adopting 
those  precautions  which  I have  named  in  my  patents,  and  in  my 
pamphlet  on  Cylinder  Condensation. 

Faithfully  yours, 

GEORGE  BASIL  DIXWELL. 

Boston,  May  9,  1877. 

No.  23  Beacon  Street. 


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REPORT 


ENGINEERS  OF  THE  U.  S.  NAVY 


MADE  AT  THE 


MASSACHUSETTS  INSTITUTE  OF  TECHNOLOGY, 


MARCH,  1877. 


BOSTON: 

FRANKLIN  PRESS:  RAND,  AVERY,  & COMPANY. 
1877. 


G a w \ n 4 

L-L.  -''■f  . 


I 

i 


Boston,  Mass.,  March  24,  1877. 


Sir  : In  obedience  to  your  orders  of  the  6th  inst.,  we  have 
witnessed  a number  of  experiments  made  at  the  Massachu- 
setts Institute  of  Technology  by  Mr.  George  B.  Dixwell,  and 
beg  leave  to  report  as  follows  : — 


1 


In  the  apparatus  employed,  steam  was  taken  from  the  hori- 
zontal tubular  boilers  which  supply  steam  for  heating  the 
buildings  of  the  Institute  of  Technology,  and  for  other  pur- 
poses. 

The  engine  is  of  the  well  known  Corliss  type,  of  8 inches 
diameter  and  24  inches  stroke  of  piston.  The  cut-off  is 
varied  by  an  Allen  governor.  The  entire  clearance  is 
itl'o  space  displacement  of  the  piston. 

The  power  developed  by  the  engine  is  absorbed  by  a fric- 
tion brake,  applied  to  the  fly-wheel. 

The  exhaust-steam  from  the  engine  passes  to  the  calori- 
meter^ which  comprises  the  following  details : — 

1.  A tank  built  of  planks  two  inches  thick,  of  about  120 
cubic  feet  capacity,  containing  a system  of  tubular  metallic 
condensing  surfaces,  the  interior  of  the  latter  being  in  com- 
munication with  the  exhaust-pipe  of  the  engine  and  with  the 
receiving-tanks  hereinafter  described.  The  body  of  the  tank 
may  be  filled  with  water  from  the  city  aqueduct,  by  which 
heat  in  the  steam  discharged  from  the  cylinder  into  the  sys- 
tem of  condensing-tubes  will  be  absorbed.  To  relieve  the 
walls  of  the  tank  from  pressure  resulting  from  the  expansion 
of  the  water  in  heating,  a small  vessel  of  ten  feet  cubical 
capacit}',  two  feet  high,  of  wood,  is  placed  above  the  large 


4 


tank  described  above,  communicating  with  the  latter  by  a 
pipe  of  two  inches  diameter.  Through  this  pipe  the  expand- 
ing water  may  rise  to  the  upper  vessel  described,  which  is 
called  the  expansion  tank.  The  escape  of  vapor  is  prevented 
by  a floating  cover  in  the  expansion  tank,  joined  to  the  walls 
by  a flexible  diaphragm.  The  large  tank,  the  expansion  tank, 
and  their  contents  and  appendages,  stand  upon  the  platform 
of  a Fairbanks  scales.  Freedom  of  movement,  within  suffi- 
ciently wide  limits,  is  maintained  by  fitting  the  pipe  connec- 
tions of  the  tank  with  rubber  tubing ; and  the  weighing  is 
accurate  within  two  pounds ; the  whole  weight,  tanks,  ap- 
purtenances, and  water,  being  8,100  pounds. 

The  tank  is  fitted  with  thermometers  for  ascertaining  the 
temperature  of  the  hydrant  water  entering,  and  of  the  water 
contained.  To  insure  equality  of  the  latter  quantity  in  all 
parts  of  the  tank  chamber,  a device  for  circulating  the  water 
is  provided,  to  be  worked  by  hand. 

The  fall  of  pressure  in  the  condenser-tubes,  below  that  of 
the  atmosphere,  is  averted  by  the  automatic  action  of  a 
reverse,  or  vacuum,  valve. 

2.  The  pipe  leading  from  the  lower  end  of  the  condensing- 
tubes,  through  wliich  the  water  resulting  from  condensation 
passes  out  of  the  large  tank,  enters  a small  tank,  which,  like 
the  others,  is  made  of  two-inch  plank.  This  tank  stands 
upon  the  platform  of  a second  Fairbanks  scales,  and  is  fitted 
with  a thermometer  for  ascertaining  the  temperature  of  its 
contents.  This  tank  may  be  emptied  through  a pipe  leading 
to  the  sewer.  The  pipe  connections  are,  like  those  of  the 
large  tank,  flexible,  so  as  to  admit  of  weighing. 

The  superheating  apparatus  consists  of  a cylindrical  boiler, 
of  iron,  seven  feet  long  and  three  feet  in  diameter,  fitted  with 
fifty  iron  tubes  two  inches  in  diameter  and  five  feet  long. 
The  latter  are  fire-tubes,  vertical,  and  six  inches  of  the  lower 
end  covered  with  water.  Tlie  superheater  is  set  in  brick- 
work, in  which  an  annular  space  allows  the  products  of  com- 
bustion to  pass  downward,  around  a part  of  the  shell.  The 


furnace  is  of  brick-work,  so  far  removed  from  the  heating  sur- 
faces as  to  prevent  direct  radiation  to  them  from  the  fuel.  In 
this  vessel  the  steam  from  the  boiler  may  be  superheated 
above  600°  F. 

The  superheated  steam  is  delivered  to  the  engine  through 
a 2|-inch  pipe.  At  the  receiving  end  of  this  pipe,  a pipe  of 
inches  diameter  delivers  saturated  steam,  the  admission 
being  regulated  so  as  to  govern  the  temperature  of  the  steam 
passing  through  the  pipe,  which  nevertheless  remains  su- 
perheated to  a degree  measured  by  a Bulkley  pyrometer, 
placed  five  or  six  feet  beyond. 

A mercurial  thermometer  is  placed  close  to  the  steam-chest 
of  the  engine,  in  the  steam-pipe,  and  another  Bulkley  pyrom- 
eter in  the  clearance  space  of  the  cylinder.  A mercurial 
thermometer  is  also  placed  at  the  point  last  mentioned. 
During  a part  of  the  experiments,  a mercurial  high-grade 
thermometer  was  placed  nearly  midway  of  the  length  of  the 
steam-pipe. 

Besides  the  pipes  described,  others,  connecting  the  engine 
directly  with  the  generator,  are  fitted.  These  are  cut  off 
from  the  former  at  will,  by  gate-valves  made  perfectly  tight. 

An  indicator  was  fitted  to  each  end  of  the  cylinder. 

The  experiments  were  made  in  pairs,  as  follows:  — 

1st,  Saturated  steam,  ^ cut-off;  followed  by  one  at  the 
same  cut-off  with  superheating. 

2d,  Saturated  steam,  cut-off;  followed  by  one  at  the 
same  cut-off  with  superheating 

3d,  Saturated  steam,  | cut-off ; followed  by  one  at  the  same 
cut-off  with  superheating. 

Diagrams  from  each  end  of  the  cylinder  were  taken,  and 
readings  from  the  pressure  gauge  and  thermometers,  and  of 
the  weighing  scales,  were  registered  every  five  minutes.  The 
large  tank  was  heated,  before  the  beginning  of  each  experi- 
ment, to  the  temperature  at  which  it  was  desired  to  close  the 
experiment;  then  emptied,  and  weighed  empty;  then  filled 
with  water  from  the  city  aqueduct,  at  the  natural  tempera- 


ture,  the  temperature  observed,  and  the  full  tank  weighed. 
Throughout  each  experiment  the  water  in  the  tank  was  kept 
in  motion,  that  the  circulation  might  prevent  differences  in 
temperature  within  it.  The  temperature  and  weight  of  the 
tank  water  at  the  end  of  the  experiment  was  registered,  after 
clearing  the  condensing-tubes  of  water.  The  water  delivered 
into  the  small  receiving-tank  was  also  weighed,  and  its  tem- 
perature ascertained  every  five  minutes.  From  these  quan- 
tities the  total  heat  of  the  steam  leaving  the  cylinder  is 
computed. 

It  was  sought  to  maintain  in  the  cylinder,  during  each  ex- 
periment with  superheated  steam,  a temperature  of  310°  F., 
and  an  initial  pressure  of  50  pounds  by  the  gauge. 

It  will  be  seen  from  the  Table  hereto  appended,  which  con- 
tains the  averages  of  all  the  observations  recorded,  that  this 
was  very  n earl 3^  accomplished. 

It  will  also  be  seen,  that,  to  maintain  the  above  tempera- 
ture within  the  cylinder,  a varied  degree  of  superheating  was 
necessary,  accordingly  as  tlie  cut-off  was  varied. 

The  relations  of  the  cut-offs,  the  pressures,  the  tempera- 
tures, and  the  losses,  will  appear  from  inspection  of  the  Table 
and  the  diagrams  appended,  the  latter  being  selected  from 
among  those  nearest  the  mean  of  the  whole.  The  dotted 
lines  on  the  latter  are  true  hyperbolic  curves  plotted  for 
comparison. 

After  the  experiments  were  completed,  the  correctness  of 
the  instruments  used  was  verified  by  the  very  accurate 
methods  of  the  Institute  of  Technology.  It  was  then  ascer- 
tained that  some  leakage  of  piston  and  valves  had  existed. 
This  leakage  affects  the  cost  of  the  power,  but  not  the  cor- 
rectness of  the  deductions  from  the  data  obtained,  in  their 
bearings  upon  the  object  of  the  experiments. 

The  experiments  of  Mr.  Dixwell  may  be  treated  as  supple- 
mentary to  those  made  bj^the  Navy  Department,  and  recorded 
in  the  second  volume  of  “ Isherwood’s  Researches  in  Steam 
Engineering,”  since  the  questions  they  are  intended  to 
answer  grow  out  of  an  investigation  of  those  records. 


7 


Mr.  Dixwell  says,  — 

“ The  object  is  to  demonstrate  two  facts  which  had  pre- 
viously been  inferred  from  an  examination  of  the  experiments 
made  by  Chief  Engineer  Isherwood  with  superheated  steam 
on  board  the  steamers  ‘ Georgeanna  ’ and  ‘ Adelaide,’  as 
described  in  the  second  volume  of  ‘ Experimental  Researches 
in  Steam  Engineering.’  These  were, — 

1.  That,  with  steam  working  expansively,  the  temperature 
of  the  cylinder  is  much  below  that  of  the  superheater. 

2.  That,  in  order  to  maintain  a given  temperature  in  the 
cylinder,  the  steam  must  be  superheated  less  for  a small 
measure  of  expansion,  and  more  for  a large  measure.” 

The  following  points  are  noticeable  features  of  the  experi- 
ments, and  of  the  action  of  the  apparatus  : — 

1.  Throughout  all  the  experiments  with  saturated  steam, 
considerable  variations  in  the  temperature  of  the  cylinder 
were  indicated  by  the  thermometer  and  the  pyrometer 
during  every  stroke  of  the  piston.  The  amplitude  of  the 
vibrations  of  the  pyrometer  extended  over  nineteen  degree- 
marks  of  the  dial.  But  throughout  the  whole  of  every 
stroke  of  the  piston,  during  the  experiments  with  superheated 
steam,  these  instruments  constantly  indicated  a fixed  degree 
of  temperature,  showing  no  vibrations  whatever. 

At  the  close  of  the  half-stroke  and  the  seven-tenths  stroke 
cut-off  experiments  with  superheated  steam,  the  same  instru- 
ments showing  no  vibrations,  the  cut-off  was  shortened 
without  change  in  the  superheating : vibrations  of  considera- 
ble amplitude  were  presently  observed  in  them. 

2.  The  remarkable  fall  of  temperature  of  the  steam  in 
passing  from  the  superheater  to  the  steam-chest,  before  enter- 
ing the  latter,  being,  for  i cut-off,  97° ; for  i cut-off,  49°  ; for 

_7_  1 Qo 

10’  • 

3.  During  experiments  with  superheated  steam,  the  open- 
ing of  the  indicators  for  preliminary  heating  was  attended 
by  a sudden  fall  of  15°  F.  within  the  cylinder,  the  tempera- 
ture gradually  rising  again  as  the  metal  of  the  indicators 
became  heated. 


8 


After  using  superheated  steam,  five  minutes  were  required 
for  a fall  of  15°,  the  steam  being  shut  off. 

It  appears  to  the  Board  that  the  record  sustains  the  views 
of  Mr.  Dixwell  so  far  as  the  scope  of  the  experiments  will 
enable  them  to  judge. 

We  are,  sir. 

Very  respectfully. 

Your  obedient  servants, 

CHAS.  H.  LORING, 

Chief  Engineer  U.S.N. 
CHAS  H.  BAKER, 

Chief  Engineer  U.S.N. 
EDWARD  FARMER, 

Chief  Engineer  U.S.N. 

Engineer-in-Chief, 

WM.  H.  SHOCK,  U.S.  Navy, 

Chief  of  the  Bureau  of  Steam  Engineering, 

Navy  Department,  Washington,  D.C. 


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10 


Pressures  in  Cylinder  above  Zero  shown  by  Indicator.  | 

1 

Mean 

Gross 

Effective 

Pressure. 

20.71 

34.99 

44.97 

18.62 

33.5 

43.71 

CO 

Moan 

Back 

Pressure. 

15  35 

15.65 

15.8 

15.15 

15.35 

15.45 

d 

(N 

Mean 

Total 

Pressure. 

36.06 

50.64 

60.77 

33.77 

48.85 

59.16 

t 21 

21. 

Fraction 
of  stroke 
uncom- 
pleted at 
Exhaust 
Closing. 

q q o q o o 

1 

•OS 

Pressure 

at 

Cushion. 

15.7 

16. 

16.5 

15.5 

16. 

15.9 

19. 

Pressure 

at 

Release. 

18.7 

29.5 

44.5 

15.1 

26. 

39.7 

1 

00 

rH 

1 

Pressure 

at 

Cut-off. 

56.9 

59.7 

61.3 

57.4 

58.8 

61.1 

17. 

Initial 

Pressure. 

65. 

66.2 

66.2 

65.9 

66.6 

66.9 

16.  1 

Boiler 
Pressure 
above  At- 
mosphere 

Gauge. 

50.4 

50.2 

50.3 

50.4 

50. 

50.2 

15. 

Total 

weight  of 

Water  con- 
sumed by 
Engine 
during  Ex- 
periment. 

lbs. 

780. 

740.75 

746.25 

722. 

705.75 

700. 

i 

Revolu- 
tions per 
Minute. 

61.46 

60.41 

58.03 

61.04 

61.44 

59.49 

13. 

Whole 
Number 
of  Revo- 
lutions 
during 
Experi- 
ment. 

7806 

5014 

3656 

11006 

6646 

4462 

12. 

Duration 
of  Exper- 
iment in 
Minutes. 

127 

83 

63 

180.3 

108 

75 

Number 

for 

Refer- 

ence. 

.-1  (N  CO  kO  <0 

11 


38. 

Total 
Heat  of 

Exliaust 

Steam 

shown  by 

Calori- 

meter in 
Thermal 

Units 

above 

zero. 

1046. 

1084.5 

1101.4 

1138.6 

1159.4 

1170.8 

CO 

Water 

per 

Gross 

Effect- 

ive 

Horse 

Rower 

per 

Hour. 

48.2 

42.2 

45.3 

35.2 

31.7 

35.8 

CO 

CO 

Water 

per 

Total 

Horse 

Power 

per 

Hour. 

27.66 

29.14 

33.54 

19.39 

21.75 

26.48 

35. 

Gross 

Effect- 

ive 

Horse 

Power. 

7.65 

12.7 

15.68 

6.83 

12.37 

15.63 

CO 

Total 

Horse 

Power. 

13.32 

18.38 

21.19 

12.39 

18.03 

21.15 

33. 

Percent- 
age of 
Loss  at 
End  of 
Stroke 
to  Whole 
Steam 
used. 

32.4 

29.3 

23.9 

18.3 

13.6 

11.5 

32. 

Per- 

centage 
of  Loss 
at  Cut- 
off to 
Whole 
Steam 
used. 

52.2 

35.9 

27.9 

27.4 

13.6 

8.9 

31. 

Loss  at 
End  of 
Stroke 
per 

Stroke. 

.01662 

.02208 

.02475 

.00625 

.00739 

.00917 

6 

CO 

Weight 
of  Steam 
alone  at 
End  of 
Stroke, 
supposing 
Satura- 
tion. 

.03473 

.05321 

.07877 

.02793 

.04712 

.07068 

29. 

Loss 

of  1 

Cut-off 

per 

Stroke. 

1 

.02682 

.02706 

.02887 

.00937 

.00742 

.00709 

28. 

Weight 
of  Steam 
alone  at 
Cut-off, 
supposing 
Satura- 
tion. 

.02453 

.04823 

.07465 

.02481 

.04709 

.07276 

27. 

Sum  of 
Column 
25  and 
Column 
26. 

.05135 

.07529 

.10352 

.03418 

.05451 

.07985 

20. 

Weight 
of  Steam 
remaining 
in 

Cylinder 
per  Stroke 
at 

Exhaust 

Closing. 

.00139 

.00142 

.00146 

.00138 

.00142 

.00141 

25. 

Weight 

of 

Water 

used 

per 

Stroke. 

.04996 

.07387 

.10206 

.03280 

.05309 

.07844 

Num- 
ber for 
Refer- 
ence. 

1 

1 

r-.  (M  CO  Tf  lO  CD 

1 

1 

12 


MEAN  DIAGEAMS.  — Experiments  op  March  15,  1877. 

Scale  of  Springs,  40  lbs.  to  the  inch. 

Water  per  Total  Horse-Power  per  hour,  37.66  lbs.  with  Saturated  Steam, 
19.39  lbs.  with  Superheated  Steam. 

SATURATED.  SUPERHEATED. 


13 


MEAN  DIAGRAMS.  — Experiments  of  March  17,  1877. 

Scale  <f  Springs,  40  lbs.  to  the  inch. 

Water  per  Total  Horse-Power  per  hour,  29.14  Ihs.  with  Saturated  Steam, 
21.75  lbs.  with  Superheated  Steam. 

SATURATED.  SUPERHEATED. 


/ 


14 


MEAN  DIAGRAMS.  — Experiments  of  March  16,  1877. 

Scale  of  Springs^  40  lbs.  to  the  inch. 

Water  per  Total  Horse-Power  per  hour,  83.54  lbs.  with  Saturated  Steam, 
36.48  lbs.  with  Superheated  Steam. 

SATURATED.  SUPERHEATED. 


